How to Identify Obsolete SharePoint Online Sites with PowerShell

Microsoft 365 has been around for many years, and it’s likely that a tenant has some obsolete SharePoint Online sites. The LastModifiedDateTime property is an unreliable basis to make the decision because background processing can update the property. This article explains how to identify obsolete sites based on usage data extracted from the Microsoft Graph. Combining the usage data with basic site properties taken from SharePoint creates a report that should help administrators to figure out what sites they should consider removing.

https://office365itpros.com/2026/07/13/find-obsolete-sites/